Glossary of terms.
Natural Hazards: Tropical Cyclones/Hurricanes, Case Studies Katrina and Heta.
Depression: An area of low air pressure. Also called a low depressions spin in a clockwise
direction in the southern hemisphere and anti-clockwise in the northern hemisphere.
Depressions are not dense therefore air rises
Anti-cyclone: An Anti-cyclone is a mass of dense heavier air therefore it sinks towards earth.
Anti-cyclones are also called highs. They spin in a anti-clockwise direction in the southern
hemisphere and a clockwise direction in the northern hemisphere.
ITCZ: Inter-tropical convergence zone is where the trade winds coming from the south-east
and north-east collide. This leads to an area of very little wind called often called the
doldrums. This is where cyclones are created.
Coriolis Force: This is the force of the earth’s rotation which causes the wind to bend. At the
edge of the ITCZ the coriolis force is strong enough to spin winds into low-pressure systems.
Jet Stream: A high speed air current circling the earth between 10-30 degrees latitude.
When a jet stream goes past a low pressure system it sucks the air out which causes more
air to rush in to fill in the void.
Latent Heat: Latent heat is released when the warm moist air condenses. This keeps tropical
cyclones warm and helps fuel them.
Eye: The eye is the middle of the cyclone it is a zone of extremely low pressure with
spiralling rising air. In a cyclone the eye is calm it is usually about 25km in diameter.
Storm Surge: A rapid rise in sea level and wave height.
High Island: Are volcanic mountainous islands, they are generally most affected by wind and
erosion during a cyclone.
Low Island: Are coral atolls and are most affected by flooding and storm surges. These
islands often have a lagoon in the middle.
Track: The path a cyclone or hurricane takes is called it’s track. Heta’s track went through
Niue and Katrina’s went into New Orleans
Key facts: Tropical cyclone Heta.
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Cyclone Heta damaged: Niue, Tonga, American Samoa,
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Formed December 25th 2003
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Niue is a single coral island of 259 square kilometres in the South Pacific Ocean at
latitude 19 south and longitude 169 west.

The main exports are Taro, honey, coconut and vanilla. Tourism is a major money
earner.

hurricane strength on New Year's Day 2004

Heta was a class five Hurricane with constant wind speeds over 250 km/h with gusts
over 300 km/h

Heta killed one person a nurse who sacrificed herself for her baby

The capital of Niue is Alofi

Niue at its highest point is 68 metres above sea level

The south-east part of Niue is uninhabitable due to the trade winds which batter it.

The North West is the most Populace part due to it being sheltered from the trade
winds. Unfortionatly this is also the side of the island which gets hit by cyclone.

80% of Niue’s foliage was stripped off by Heta.

Those plants that survived received so much salt spray that many of them died
anyway this provided a major fire-risk.

Heta passed Niue about 70km off the island.

Heta’s storm surge was 4-7m

Heta hit Niue on the 6th of January 2004

Dive Niue was a major tourist activity and business which was destroyed by Heta.

The estimated cost of re-building Niue was 20 million dollars

Tropical cyclones and Hurricanes alike have a barometric pressure or air pressure of
970 Hpa or less

The Niue people were given 2 days warning about Heta coming and therefore could
plan for and prepare for it’s arrival

Niue gets around 2000 tourists a year.

Heta moved in a south-southeast direction to collide with Niue.

New Zealand provided 5 million in aid to Niue.

France provided Niue with Kit-set homes after Heta had struck

Waves which hit Niue exceeded 10m high

Waves washed inland at speeds of 100kp/h bringing with them destroyed coral from
the ocean floor.

the EU gave over 700,000. NZ sent two airforce hercules plus ships with supplies to
help rebuild.

Seventy eight people were airlifted to NZ four of them required medical treatment

Alofi was moved away from the coast into the centre of the island.

Hundreds of homes destroyed.

200 residents made homeless – 10% of population.

The hospital was basically destroyed.

Fresh water supplies contaminated with salt water

Sewage pumps no longer worked.

No running water available.

People traumatised and needing counselling.

Hotel Niue destroyed.

$240,000 loss of crops, i.e. coconut and fruit plantations.

Loss of tourism income from expected 2700 tourists (based on 2003 statistics)

Satellite dishes and phone systems knocked out.

Bulk fuel storage facility ruined and all fuel leaked into the sea.

Salinisation of the water table occurred as the salt water contaminated the fresh.

The effects of the waves reached up to 200m below the surface of the water.

Soil was damaged by the deposition of silt from the storm surge.

Soil became inhospitable to plants due to salt contamination.

New zoning restrictions have been implemented so people do no build in areas
susceptible to cyclones.

The ocean has to be at least 26.5 degrees C to generate enough energy to form a
tropical cyclone.

Cyclone Heta had a barometric pressure of 915 hpa
Katrina

Katrina’s eye was 46.3 kilometres in diameter

Barometric pressure of 902 hpa

Wind speeds of over 280 kp/h

Hurricane Katrina formed over the Bahamas

The ocean was 27 degrees prior to the hurricane forming

Hurricane Katrina cost 4.25 billion US dollars

Katrina hit the Gulf Coast Mississippi, Louisiana, and Florida were the worst hit.

80% of Louisiana was flooded

1836 people died

Formed August 23 2005

Lake Ponchartrain and the Mississippi river border New Orleans.

Much of Louisiana lies below sea-level and below the levels of Lake Ponchartrian and
Mississippi river.

1.2 Million residents of the Gulf Coast were covered under a mandatory or voluntary
evacuation order

57 emergency shelters were established in coastal communities, with 31 additional
shelters available to open if needed

80% of the 1.3 million residents evacuated

8.5 metre storm surges

10 A.M august 28th Katrina was upgraded to a category 5

Louisiana Superdome provided shelter for over 26,000 people and provided food
and water for several days as the storm struck

August 29th Katrina storm surge caused 53 different Levee breaches submerging
eighty percent of New Orleans

Three million people left without electricity

Rainfall of around 200-250 mm

The Airport was closed therefore people could not evacuate

62.3 billion in aid was given for the victims

58,000 of the national guard were activated to deal with the storms aftermath
troops came from all 50 states

One Murder and one suicide occurred at the Superdome

Dead bodies were seen floating around the streets of New Orleans

Housing assistance was provided for more than 700,000 applicants

100,000 people live in FEMA provided trailors

Kuwait donated $500 million, Qatar and The U.A.E each gave 100 million

Other nations to give aid were South Korea (30 million), Australia (10 million), India,
China (5 million), NZ (2 million), Pakistan (1.5 million), and Bangladesh (1 million).

The storm surge also completely obliterated the Chandeleur Islands.

An area of 560 km2 was completely transformed into water by Katrina

As part of the clean-up effort the flooded land was pumped into lake Pontchartrian.
This water contained contaminants such as raw sewage and has sparked scientific
concern for the community

Only 40% of New Orleans residents returned to the city

Amount collected by The American Red Cross’ hurricane relief fund: $2.1 billion

August is in the middle of the Hurricane season for the Northern Hemisphere

Friday, August 26th at 10 am Katrina had strengthened to a category 3 hurricane in
the Gulf of Mexico.

The predicted track was revised and the NHC issued a hurricane watch for south
eastern Louisiana which area includes New Orleans at 10 am Saturday 27 th.

Many residents fled the New Orleans area which led to mass congestion on the
roads leading out of New Orleans it also led to an oil crisis as many people tried to fill
up.

Many of the rich were able to evacuate while the poorer largely black community
were not able to evacuate.

The Levee’s were breached in over 50 different places.

Looters took what they could from stores.

The relocated evacuee’s caused massive crime spikes in neighbouring states who
took them in. Murders, robberies etc all increased with the influx of people from
New Orleans.